The recent “#Monday Musings Book List” published on The Strategy Bridge had a number of excellent reading recommendations, but one in particular deserves some further discussion among budding strategists seeking to understand their world more clearly. Thucydides’ History of the Peloponnesian War is a book that all who seek to understand the influence of war must read. It tells the tale of great power conflict between the Greek city states of Athens and Sparta in a war that would last almost 30 years. The war would end in Athenian defeat; but desolation, destruction, and the loss of power and prestige were common to all those drawn into the vortex of this epochal war. Thucydides provides a cautionary tale about the use of war as a tool of policy, which ensures his work has an enduring relevance worthy of further discussion.
Thucydides intended his work to be “a possession for all time,” and through reading The Peloponnesian War we come to realise the complexities of modern life have not rendered everything experienced by past generations irrelevant to the problems of today. In fact, as he intended, Thucydides provides a sound basis from which to discover how best to approach the complex problems facing contemporary strategists through allowing us to better understand war’s continuities and discontinuities.
Thucydides charts the impact of war on the character of the states involved. He uses Athens’ transformation as a cautionary tale about what war will do to a state unprepared for its influence and of the cost of applying power unwisely or unjustly in the pursuit of a political objective. His writing is grounded in the understanding that war’s nature is inextricably linked to human nature, which in turn shapes the strategic and military culture that manifest in war’s character and the political objectives for which it is fought. Through a narrative approach, his work serves as a warning about the moral decline of society over the course of protracted war. In doing so he demonstrates several points relevant for all wars, including today's: War's nature is unchanging and is based on the contest for power. “Fear, honour, and interest” are human characteristics immutable through time and have generally been the cause of wars throughout history. These characteristics shape strategic and military culture and in turn the character of a given war. And the creation of a political objective based on a state's vital interests is imperative in the formulation of a winning strategy.
To assist in justifying the continuing importance and relevance of Thucydides it is helpful to analyse his work through the prism of the nature and character of war. Accordingly, this article will analyse Thucydides’ judgements about the nature of war by examining how the Peloponnesian War was shaped by alliances, competing perceptions, and geopolitics. It will use this as the basis to then discuss the character of the war and its relationship to change—specifically the interrelationship of the political objective with strategic and military culture and the character of the war itself.
THUCYDIDES AND THE NATURE OF WAR
Thucydides recognised that humanity has a nature, the imperfections of which will frequently lead to war rather than peace, based on a desire for power. For those of us who believe power is the central organising principle in international affairs, The Peloponnesian War reminds us that its judicious use distinguishes the long-lasting empires from those that flame brightly and then disappear. Thucydides does not set out to be a theorist of war, but rather to use events to elucidate the nature and consequences of human conflict and the pursuit of power. At the beginning of the war he uses Pericles to tell us there is a cost to achieving and wielding power, and only those willing to bear the cost of war can achieve greatness. This theme permeates the book as Thucydides attempts to show that fundamental to war’s nature is the depths that men will go to acquire, hold, and exercise power. This is a cautionary lesson in Athens’ case. Initial successes gained Athens great power, but they also intensified great power rivalries and created the hubris that ultimately led to its desolation. Thucydides and modern historians alike would probably suggest Athens’ fate was a result of its failure to understand the continuities of war that should have guided and constrained, rather than emboldened their actions.
Modern strategists must appreciate how Thucydides points out history’s utility in contextualising human decision making, emotions, and actions—particularly in understanding fear, honour, and interest as the root causes for war. The perception of these inherently human attributes is fundamental to a state’s conception of its vital interests and in turn its political objective. This dynamic is most clearly articulated when Thucydides states that “the growth of the power of Athens, and the alarm which this inspired in Sparta, made war inevitable.” The Peloponnesian War demonstrates that power transitions are difficult and can force the creation of complex, often volatile, alliances that undermine the stability they seek to create. The Corcyra–Corinth debate in Book One shows how local conflicts can take on larger dimensions in a nascent power struggle based on such complex alliance structures. Under these circumstances rational political objectives can become skewed by fear, honour, and interest, in turn destabilising the existing order and bringing power struggles closer to all out war. This is a subject of particular relevance for contemporary strategic calculations, where the United States’ alliances in both Europe and Asia still have the potential to lead to war with Russia and China based on local miscalculations or threats to the interests of junior alliance partners. Under such conditions these alliances create significant risk of conflagration through a response driven by fear and honour, which may in fact be counter to the United States’ actual interests.
Thucydides tells us there is a tipping point where a rising power becomes too powerful to contain. By this point, conflict between near equals may present as an inevitability, particularly when junior allies are agitating for action from the dominant partner. In such circumstances, war’s political objective can be heavily influenced by fearing the costs of not going to war as much as a fear of war itself. However, as demonstrated by Sparta and Athens, this decision is also shaped by a state’s prevailing strategic and military culture. Sparta was the established power seeking to maintain the status quo, while Athens was the rising, revisionist power wishing to reshape the world to suit its interests. Therefore at the outset of the war Thucydides is able to explain how one empire’s honour sparked another’s fear, which caused the interests of both to clash. This dynamic allowed alliance politics to push tensions to a breaking point such that it became a question of which side could justify first the use of military power to suit its interests.
THUCYDIDES AND THE CHARACTER OF WAR
If the nature of war and humanity made the conflict inevitable, it was the character of the Peloponnesian War and its link to strategic and military culture that marked it as a tragedy, and therefore an important text for contemporary strategists. Each time Athens overreaches, it seems to suffer reversals to the detriment of their existing position. This demonstrates the immaturity of their strategic culture, which seemed to be based on brash hopefulness rather than dour circumspection. Indeed, Thucydides describes the difference between the protagonists as “the slowness and want of energy of the Spartans, as contrasted with the dash and enterprise of their opponents.” While this comparison seems unfavourable to Sparta, it was this very way of life that gave them stability and continuity of strategic culture, which, perhaps, led to more effective long-term decision-making. In contrast, Athenian culture was, in Thucydides’ estimation, increasingly marked by spasmodic strategy-making and an accompanying impulsiveness in warfare, two factors that contributed heavily to their eventual defeat.
Thucydides demonstrates that the character of war is emergent, dynamic, and best understood through the medium of combat, where any flaws in strategic and military culture are laid bare. Athenian strategic culture was initially shaped by ideals and values, even though a double standard existed between the democratic norms inside the poleis and the way they undertook relations with competitors. These ideals shaped their image of themselves and a belief (as articulated by Pericles) in the right to rule others, and hence a willingness to use military force to achieve their interests. Initially, Athenian and Spartan military cultures were at odds: a maritime versus a land power with strategies of exhaustion versus that of annihilation. However, over the course of the war these military cultures discernibly changed, leaving them more closely aligned. Indeed, Sparta’s adaptation to fighting at sea and Athens’ on land is best evidenced by the ironic engagement at Pylos, which demonstrated how military cultures must adapt to the character of the conflict in which they are involved or risk losing the war altogether.
It is important to point out, however, that the changes in culture Thucydides highlights are important for us to understand in detail because change may not actually be for the better. Thucydides shows us that by removing the civilised restraints on human behaviour built up so tenuously over time, war can barbarise us; and, like a plague, this can destroy all the good that a civilisation has achieved. So it was for Athens, who adopted an ends justifies the means approach to the conflict. To illustrate this point early in the war, while Athens is in the grips of plague, Thucydides cites Pericles’ attempts to convince Athens that a compromise on values is actually worth the costs to its prestige that will be incurred:
Hatred and unpopularity at the moment have fallen to the lot of all who have aspired to rule others; but where hatred must be incurred, true wisdom incurs it for the highest objects. Hatred is also short-lived; but that which makes the splendour of the present and the glory of the future remains forever unforgotten.
This speech poses questions about whether a state can respect who they are forced to become as a result of compromising on their beliefs purely to succeed in war. Is the cost of what a state can lose in terms of honour worth what it seeks to gain from pursuing its perceived interest? Williamson Murray would suggest not, as he believes that Thucydides’ gravest warning came from his description of “the slow and steady decline in the behaviour of the opposing sides.” Athens particularly, could no longer claim to be a benevolent empire as the war progressed, with their actions in Melos actually demonstrating the decay of the Athenian state—not its enhanced power. The famous line from the Melian Dialogue: “Right…is only in question between equals in power… the strong do what they can and the weak suffer what they must,” is not in fact the truism that some assert. Rather, it is a warning to the powerful that acting because you can is often counter to the outcome you seek to achieve. This is an observation as relevant to the great power politics of today as much as it was to that of fifth century Greece.
The Athenian response to the Melians actually shows how far their ideals had fallen, rather than the power they believed they had gained. Indeed, “the Athenians were now willing to slaughter the Melians without considering the potential negative consequences to their own future strategic interests,” clearly demonstrating the short-termism that had come to dominate Athenian strategic culture. In fact, the Melians are perhaps designed by Thucydides to prove this very point when they say:
How can you avoid making enemies of all existing neutrals who shall look at our case and conclude from it that one day or another you will attack them? And what is this but to make greater the enemies that you have already, and to force others to become so who would otherwise never thought of it?
This was a shrewd warning and echoes Spartan attempts to help Athens understand the limits of power after its defeat at Pylos. They encouraged Athens to avoid letting their pride become hubris and to use their new-found position wisely, or find themselves imperiled as Sparta had. However, their appeal to Athens’ better nature fell on deaf ears as Athens sought to escalate the conflict rather than agree to peace. Thucydides highlights the tragedy of Athens letting slip the opportunity for a grand peace that could benefit both powers, instead allowing war’s tendency to greater extremes pervade in the absence of the restraint of rational policy. The outcome was a descent into a cycle of brutality and vengeance that further sullied Athenian strategic and military culture to the point where the slaughter at Melos seemed the logical extension of the abandoned intentions for Mytilene. Athens may have been ascendant, but Thucydides forces us to question whether it was worth winning if the world Athens’ strategy created was overwhelmingly against them. Thucydides, therefore, remains important because this debate still shapes strategic and military culture today, with the result defining who a state has become once the war is concluded. This is one of the most important reasons strategists must continue to advocate for the reading of The Peloponnesian War.
Ultimately, Thucydides tells us, war is about people, and as they change based on the influence of war, so must the cultures they create:
Reckless audacity came to be considered the courage of a loyal supporter; prudent hesitation, specious cowardice; moderation was held to be a cloak for unmanliness; ability to see all sides of a question incapacity to act on any. Frantic violence became the attribute of manliness; cautious plotting a justifiable means of self-defence.
The moral decline of Athens culminated in their decision to invade Syracuse where Athens proved they had become victims of their own success, incapable of seeing risk through potential reward. Athens had lost its grip on reality as it sought to continue expansion because it knew of no other course. This created a “with us or against us; kill or be killed” mentality that demonstrated Athens’ strategic myopia. The strategic culture that existed pre-war where fear at least drove a semblance of rationality in the political objective and strategy was gone. It was replaced by brashness and arrogance that failed to see the strategic vulnerabilities it created.
By failing to understand the vulnerabilities inherent in imperial overstretch the Athenians were left exposed in a two-front war with insufficient resources to satisfy either. They found themselves reinforcing a sideshow in Sicily while the main effort in Greece remained unresolved. This created the crucial opportunity for Sparta to turn the tables in the war through the adoption of a strategy based on exhaustion. In so doing the Spartans showed a more pragmatic strategic culture than Athens possessed at the time, which would be crucial to the result of the Sicilian expedition and the eventual termination of the war. The reversal this signified for Athens is all the more tragic for the decline in Athenian strategic and military culture that it represented.
Ultimately, Thucydides’ enduring relevance lies in the fact that he forces us to wrestle with the notion that war, as a contest for power, strips bare human nature under the pressure of conflict—and the results are not appealing. The Peloponnesian War shows how strategic perceptions based on the innately human frailties of fear, honour, and interest lead a state to war. Thucydides then warns us that during conflict a state’s collective morality can decline under the strain of prolonged war based on the choices it makes. He helps us understand that creating a winning strategy is all about these choices, which are shaped by a state’s strategic and military culture. Some choices will be right and others will not; but the outcome of these choices will eventually define victor and vanquished. He provides a powerful case study of continuity and change in war; and as with Clausewitz, the lessons he identifies should not be reduced to glib epigrams. Indeed, it is the richness of his narrative that provides the convincing examples for strategists to dissect of how the political objective, as well as strategic and military culture, changes based on war’s influence. Thucydides chronicled an epochal war so as to make the conflict available for examination by future generations in the hope of producing greater understanding of war itself. That contemporary students of war still commend him to us for insights on the nature and character of war proves that he was indeed successful in creating a history that is truly a possession for all time.
Mark Gilchrist is a serving Australian Army Officer. The views provided here are his own and do not reflect any official positions.
 Thucydides, translated by R.B. Strassler (ed), The Landmark Thucydides: A Comprehensive Guide to The Peloponnesian War (New York: Touchstone, 1998), 15.
 Ibid., 43.
 Ibid., 12.
 The Melian dialogue is an example of this dynamic. The killing of all the males and selling of women and children into slavery is not to be celebrated as a demonstration of power, but mourned for what is says about a state that debases itself through using power in this way. Ibid, 355.
 Williamson Murray, "Thucydides: Theorist of War," Naval War College Review (Vol 66, No 4: Autumn 2013), 31.
 Thucydides, 126.
 Men specifically, because Thucydides is notable for the absence of women in his work.
 Karl Walling, "Thucydides on Policy, Strategy, and War Termination," Naval War College Review(Vol 66, No 4: Autumn 2013), 79.
 Thucydides, 16.
 Ibid., 21-22.
 Ibid., 24.
 Ibid., 41.
 Ibid., 43.
 Be it through the actions of Cleon, Alcibiades or any other politician who was able to sway the emotion of the Poleis to seek glory at the cost of rational consideration.
 Thucydides, 351.
 Ibid., 539.
 Ibid., 481.
 Ibid., 114.
 At Pylos the evolution of military culture was clearly demonstrated when Athenians found themselves defending on Spartan land, from the Spartans who were attacking Athens from the sea. Thucydides, 232.
 Ibid., 126.
 Murray, 39.
 Thucydides, 353.
 Murray, 40.
 Thucydides, 353.
 Ibid., 233.
 Athens initially decided to execute all residents of Mytilene after their attempted revolt against Athenian control. The demagogue, Cleon, argued most strongly for this, warning that the three failings most fatal to empire were ‘pity, sentiment and indulgence’ and that Athens must show strength and resolve in the face of this insult. Ibid., 175-183.
 Ibid., 199-200.
 Ibid., 367, 409-410.
 Ibid, 438-443.